1. Field of the Invention
This invention relates to a vehicle mirror which is suitable for a vehicle side mirror and the like, more particularly a vehicle mirror having a function of anti-halation and a function to remove water droplets with a piezo-electric vibrator and the like.
2. Description of the Related Art
As the conventional type of the vehicle mirror, a technology shown in FIGS. 15 and 16 can be applied.
FIG. 15 is a partial sectional view for showing a vehicle mirror having a conventional function to prevent halation. FIG. 16 is a sectional view for showing a vehicle mirror having a function to remove water droplets which was disclosed in Jap. U.M. Laid-Open No. Sho 61-30552.
In the vehicle mirror shown in FIG. 15, a holder 31 is formed with a releasing part 32 and a holding part 33. Anti-halation mirror member 34 having a convex surface with a predetermined curvature is stored within the holder 31. The anti-halation mirror member 34 is comprised of a front transparent glass member 35 exposed from the releasing part of the holder 31, a rear mirror member 37 having a reflection film (not shown) fixed to a rear side of the front transparent member 35 by adhesive agent 36 in a desired spaced-apart relation thereto and a liquid crystal 38 sealingly enclosed between the rear mirror member 37 and the front transparent member 35. A circumference of the front transparent member 35 is held by the holding part 33 of the holder 31 through a spacer 39.
In the conventional type of vehicle mirror constructed as above, when the liquid crystal 38 of the anti-halation mirror member 34 is electrically energized, a transmission factor of the light beam in the liquid crystal 38 is increased or decreased to cause a reflection factor of the rear mirror member 37 to be varied. Accordingly, an appropriate adjustment of an applied voltage for the liquid crystal 38 enables reflected light from the anti-halation mirror member 34 caused by head lamps of a subsequent vehicle to be dampened and to prevent a driver from being dazzled.
In turn, in the case of the vehicle mirror shown in FIG. 16, a holder 41 is supported at a vehicle body (not shown) through a stay 42, and a glass mirror member 43 having a reflection film (not shown) is installed within the holder 41. A piezo-electric vibrator 44 for generating vibration under an effect of piezo-electricity is installed between the holder 41 and the stay 42. A driving circuit 46 and an operating switch 47 in a vehicle compartment are connected in series between the piezo-electric vibrator 44 and a power supply 45.
In the conventional type of the vehicle mirror constructed as described above, if water droplets are adhered to the surface of the mirror member 43, the operating switch 47 in the vehicle compartment is operated to generate a vibration of the piezo-electric vibrator 44 and then the vibration is transmitted to the mirror member 43 through the housing member 41. Thus, it is possible to remove the water droplets adhered to the surface with the vibration of the mirror member 43 and to clarify an image in the mirror member 43.
In this case, the conventional type of vehicle mirror shown in FIG. 15 possesses an anti-halation function, but function to remove the water droplets. In addition, the prior art vehicle mirror shown in FIG. 16 possesses an ability to remove water droplets, but cannot function to prevent halation.
As a practical means for integrally combining both functions to get a vehicle mirror having both functions, it has been proposed to provide a configuration in which the piezo-electric vibrator 44 is directly adhered to the rear mirror member 37 of the anti-halation mirror member 34 as shown in a partial sectional view illustrating an example of the vehicle mirror having an anti-halation function shown in FIG. 17. However, if the aforesaid piezo-electric vibrator 44 is directly adhered to the rear mirror member 37, a vibration of the rear mirror member 37 is accommodated by the liquid crystal 38 when the rear mirror member 37 is vibrated ultrasonically, and then an ultra-sonic vibration is not efficiently transmitted from the rear mirror member 37 of the aforesaid anti-halation mirror member 34 to the rear transparent member 35. In case that clearances between the front transparent member 35 and the rear mirror member 37 are different at each of the portions due to a difference of a linear expansion coefficient under a temperature condition at the time of adhesion and there is a large clearance around the adhered portion, the liquid crystal 38 is discolored and becomes dark. In turn, if there is a small clearance around the adhered portion, the liquid crystal 38 shows a phenomenon of discoloring to a white color.
In view of the foregoing, it is the first subject matter of the present invention to provide a vehicle mirror capable of improving the efficiency of removal of water droplets by the piezo-electric vibrator. It is the second subject matter of the present invention to provide a vehicle mirror capable of realizing the anti-halation function, improving an efficiency of removing water droplets with a piezo-electric vibrator and having both anti-halation function and water droplets removing function.